Metal-chalcogenide cluster compounds

Perspectives for fabrication of improved oxygen electrodes at a low cost have been offered by non-noble, transition metal catalysts, although their intrinsic catalytic activity and stability are lower in comparison with those of Pt and Pt-alloys. The vast majority of these materials comprise (1) macrocyclic metal transition complexes of the N4-type having Fe or Co as the central metal ion, i.e., porphyrins, phthalocyanines, and tetraazaannulenes [6-8] (2) transition metal carbides, nitrides, and oxides (e.g., FeCjc, TaOjcNy, MnOx) and (3) transition metal chalcogenide cluster compounds based on Chevrel phases, and Ru-based cluster/amorphous systems that contain chalcogen elements, mostly selenium. 

Nitrogenase is another big target of cluster synthesis. The X-ray elucidation of the active center of the Fe-Mo cofactor and P-cluster (5) has accelerated the efforts to find rational preparative methods of trinuclear or cubane-type clusters containing molybdenum (6-9). The raft cores in these cluster complexes are one of the general structural units also in solid-state compounds, and the mutual relationships are very important. A number of review articles are now available on the syntheses, structures, and other properties of metal chalcogenide cluster compounds (6, 7,10-24). 

Group 6 Metal Chalcogenide Cluster Complexes and Their Relationships to Solid-State Cluster Compounds Taro Saito... 

GROUP 6 METAL CHALCOGENIDE CLUSTER COMPLEXES AND THEIR RELATIONSHIPS TO SOLID-STATE CLUSTER COMPOUNDS... 

Better yields for MgSg " (M = Mo, W) are obtained when MgClig, NaSH, and NaOBu are refluxed in pyridine. In these reactions the NaOBu serves as a proton abstractor and the chalcogenide clusters are isolated as the pyridine adducts (14, 70, 71). The chemistry and structural variations of the group 6 metal chalcogenide clusters were recently reviewed in this series, and the reader is referred to this publication for further information on these compounds (72). 

B7.27 Group 6 metal chalcogenide cluster complexes and their relationships to solid-state cluster compounds... 

Clearly, the way to understand the tailoring of nanomaterials is the follow-up of the chemical process. This has been done with the mthenium-chalcogenide materials. Thus using transition metal molecular cluster compounds paved to a certain extent, the bottom-up approach for chalcogenide catalysts in the nanoscale domain. We believe we have given a fairly comprehensive account of this chemical process. The use of the various clue techniques such as e g., NMR, XPS, XRD, not all mentioned in this chapter, provided information as to the nature of the rathenium-selenide material. Such information caimot be obtained if limited solely to py-rolsis, and to electrochemical techniques. 

Abstract This review highlights how molecular Zintl compounds can be used to create new materials with a variety of novel opto-electronic and gas absorption properties. The generality of the synthetic approach described in this chapter on coupling various group-IV Zintl clusters provides an important tool for the design of new kinds of periodically ordered mesoporous semiconductors with tunable chemical and physical properties. We illustrate the potential of Zintl compounds to produce highly porous non-oxidic semiconductors, and we also cover the recent advances in the development of mesoporous elemental-based, metal-chalcogenide, and binary intermetallic alloy materials. The principles behind this approach and some perspectives for application of the derived materials are discussed. 

X-ray crystallography, 40 20-21 synthetic models, 40 23-48 xanthane oxidase, 40 21-23 chalcogenide halides, 23 370-377, 413 Chevrel phases, 23 376-377 metal-metal bonding, 23 330, 373 structural data, 23 373-376 as superconductors, 23 376 synthesis, 23 371-372 chloride, 46 4-24, 35-44 heterocations of, 9 290, 291 cluster compounds, 44 45-46 octahedral, 44 47-49, 53-63 electronic structure, 44 55-63 molecular structure, 44 53-54 synthesis, 44 47-49 rhomboidal, 44 75-82 solid-state clusters and, 44 66-72, 74-75, 80-82, 85-87 tetrahedral, 44 72-75 triangular, 44 82-87 cofactor, 40 2, 4-12 anaerobic isolation, 40 5 molybdopterin and, 40 4-8 reduced form, 40 12 synthesis, 40 8-12 xanthine oxidase, 45 60-63 complexes... 

Heterometal alkoxide precursors, for ceramics, 12, 60-61 Heterometal chalcogenides, synthesis, 12, 62 Heterometal cubanes, as metal-organic precursor, 12, 39 Heterometallic alkenes, with platinum, 8, 639 Heterometallic alkynes, with platinum, models, 8, 650 Heterometallic clusters as heterogeneous catalyst precursors, 12, 767 in homogeneous catalysis, 12, 761 with Ni—M and Ni-C cr-bonded complexes, 8, 115 Heterometallic complexes with arene chromium carbonyls, 5, 259 bridged chromium isonitriles, 5, 274 with cyclopentadienyl hydride niobium moieties, 5, 72 with ruthenium—osmium, overview, 6, 1045—1116 with tungsten carbonyls, 5, 702 Heterometallic dimers, palladium complexes, 8, 210 Heterometallic iron-containing compounds cluster compounds, 6, 331 dinuclear compounds, 6, 319 overview, 6, 319-352... 

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